DC/DC converters are fundamental parts of many electrical systems such as electric fuel cell systems and photo voltaic panel systems. A DC/DC converter is typically used to stabilize a DC voltage, to convert DC voltage from one level to another to supply a DC/AC inverter, and to provide galvanic isolation to an electrical circuit (e.g., isolating a load from a power source, or isolating an AC power grid from a power source (via a DC/AC converter)). The input connection to a DC/DC converter is typically a two-terminal source, whereas the output is typically a split or dual DC bus including a positive terminal, a negative terminal, and a center point. A three-terminal output is generally used to supply DC power to a three-level inverter.
DC/DC converters may have high-voltage spikes that appear across rectifier diodes contained within the converters. These voltage spikes can cause damage to the components within a DC/DC converter and are typically clamped by additional diodes that conduct and feed excess energy into a capacitor. The capacitor, in turn, is discharged after receiving energy, thereby allowing the capacitor to settle at a stable voltage. Typically, one of two methods is used to discharge the capacitor. First, a passive resistor is used to dissipate the energy stored in the capacitor. Second, in an active, powered, configuration, a small DC/DC converter may be used. These two options present a choice between advantages and disadvantages. Using a passive resistor to dissipate stored energy creates additional power losses, but is inexpensive. Using a second DC/DC converter decreases the power loss, but adds to the cost and complexity of the circuitry.
A DC/DC converter may also have a high amount of ripple current at the input side of the converter, which is typically undesirable. Additional DC filtering components are usually added to the DC/DC converter across the converter input to reduce ripple current.